Wound packing

ABSTRACT

The present invention relates to a wound packing material, suitable for use in negative pressure wound therapy, comprising a body of a porous material, the body comprising frangible regions defining a plurality of portions, the frangible regions allowing the portions to be selectively removed from the body. The invention further relates to methods of manufacturing the wound packing material, and to methods of its use.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.14/328,323, filed Jul. 10, 2014, entitled WOUND PACKING, which is acontinuation of U.S. patent application Ser. No. 13/201,427, filed Sep.14, 2011, entitled WOUND PACKING, which is a U.S. National Phase of PCTInternational Application No. PCT/GB2010/000228, filed on Feb. 10, 2010,designating the United States and published on Aug. 19, 2010 as WO2010/092334, which claims priority to Great Britain Patent ApplicationNo. 0902368.0, filed on Feb. 13, 2009. The disclosure of all of theprior applications are incorporated by reference herein in theirentireties and should be considered a part of this application.

BACKGROUND OF THE DISCLOSURE Field of the Invention

The present invention relates to a porous wound packing material andmethods of its manufacture and use. In particular it relates to a woundpacking material which is adapted to allow it to be easily shaped andconfigured to the shape of a wound. Such wound packing materials areparticularly suitable for negative pressure wound therapy (NPWT).

Background

NPWT is a relatively new treatment for open wounds. Typically in NPWTthe wound cavity or surface is filled or covered with a material thatallows the transmission of a partial vacuum (i.e. does not completelycollapse) to the wound bed when a negative pressure is applied to thewound area, and also allows fluids to pass from the wound bed towardsthe source of negative pressure. There are two primary approaches toNPWT, i.e. gauze or foam types. The gauze type (also referred to as theChariker-Jeter technique) involves the use of a drain wrapped in gauzetopped by a sealed dressing. The foam type involves the use of foamplaced over or in the wound. The present invention is directed primarilytowards the foam type of NPWT.

In foam based NPWT the wound cavity is filled or covered with a porousfoam packing material and covered over and sealed with flexible sheet (adrape) that is fairly impermeable to fluids. A tube is inserted under orthrough the drape into the wound site and its distal end is connected toa vacuum source (commonly a pump). The wound cavity, enclosed by thedrape and tissue, contracts under the force of atmospheric pressure andcompresses the packing material visibly. Gross tissue movement ceasesafter a few tens of seconds and fluid flow from the wound (withdrawnfrom the tissue) ensues. The fluid is transmitted through the packingmaterial and up the vacuum tube to a collection receptacle positionedbetween the distal end of the tube and the vacuum source. The woundpacking material mechanically supports the tissue to which it isapplied, and also allows the free flow of fluids away from the site whena vacuum is applied, even when compressed. A good material for thisapplication is hydrophobic, reticulated polyurethane foam of very highfree internal volume.

The packing material for use in NPWT must be shaped to fit the wound tobe packed. This is typically achieved by the medical practitioner(typically physician or nurse) cutting a preformed block of foam(usually a cuboid) to approximately fit the wound using a scalpel, knifeor scissors. This operation can be complex, time consuming and messy forthe medical practitioner, and indeed can be dangerous with thepossibility of particulate foam material contaminating the wound site orof an accident during the cutting process. Accordingly, the process ofshaping the wound dressing is currently an unaddressed problem in thefield of NPWT which is a barrier to its effective and widespread use.

SUMMARY OF SOME EXEMPLIFYING EMBODIMENTS

According to the present invention there is provided a wound packingmaterial comprising a body of a porous material, the body comprisingfrangible regions defining a plurality of portions, the frangibleregions allowing the portions to be selectively removed from the body.

The term frangible is intended to mean that the material has beenweakened in some manner which allows the portion to be removedrelatively easily (e.g. manually) from the body without substantiallydamaging the remainder of the body, but where the overall structure ofthe body is sufficiently strong that the body remains intact duringnormal use, i.e. in the absence of manipulation to remove a portion. Itis highly preferred that the portions can be removed manually, withoutthe use of additional tools such as scissors, knives, scalpels etc. Thisallows a medical practitioner to remove portions to achieve a desiredshape of the body quickly and simply without the need to use additionaltools.

Preferably the frangible regions are defined by partial pre-cuts formedin the body.

Use of the term partial pre-cuts is intended to mean a region of thebody where the material of the body has been removed or severed to atleast partially separate a portion of the body from the rest of thebody, but where sufficient material of the body has been left such thatthe body retains its general structural integrity, i.e. sufficientintegrity for general storage, handling and use as a wound packingmaterial. However, the remaining material is sufficiently weak (i.e.frangible) that it is relatively easily severable with manually appliedforce, e.g. by a medical practitioner tearing the portion from the body.

It should be noted that the term partial pre-cuts is intended to coverboth situation where material is removed by cutting or otherwiseremoving or severing regions of a preformed body of porous material, andalso where the pre-cuts are formed during initial production of thebody, e.g. formed during a moulding process.

Preferably the wound packing material is a wound packing foam suitablefor use in negative pressure wound therapy (NPWT). Particularly suitablefoams for NPWT include polyurethane foam, typically reticulatedpolyurethane foam of very high free internal volume, e.g. 80% or higher,preferably 90% or higher free internal volume. Typical foams used inNPWT have porosities in the range 30-60 ppi (pores per inch) and porediameters in the range 300-800 μm. However, other suitable foams areknown in the art and may be equally suitable. In general suitable foamshave an open porous structure, to allow transmission of the negativepressure to the wound bed, and sufficient mechanical strength to preventthe negative pressure (typically approximately 80-125 mm Hg belowambient atmospheric pressure) from substantially collapsing thestructure of the foam.

It is highly preferred that the wound packing material is sterile. Thiscan be achieved using conventional sterilisation techniques which areknown for sterilising surgical foams and dressings.

It will be clear to the person skilled in the art that size and shape ofthe selectively removable portions will be determined by the number offrangible regions provided per unit volume of the body, and the numberof different orientations and configurations that the frangible regionsare provided in.

As mentioned above, the frangible regions are preferably defined bypartial pre-cuts within the body—the following description will focus onembodiments whereby the frangible regions are formed in this way, but itwill be understood that frangible regions could be formed in othermanners (e.g. selectively weakening the foam structure at selectedregions using chemically agents or heat) and that such variants arewithin the scope of the present invention.

It is preferred that the partial pre-cuts are generally planar. Inparticular, flat planar partial pre-cuts are preferred as they providefor regularly shaped portions. However, it is perfectly possible thatthe planes could be curved where a curved profile on an exposed regionof the body following removal of the portions is preferred.

Suitably the body comprises a first set of substantially parallel planarpartial pre-cuts in first orientation. The set may comprise a pluralityof planar pre-cuts, each planar pre-cut comprising a series ofindividual pre-cuts, each individual pre-cut being spaced from theadjacent pre-cut by a gap. The individual pre-cuts are aligned with theplane defined by the planar parallel partial pre-cut. Preferably theparallel planar partial pre-cuts of the set are regularly spaced. Whereone set of parallel planar partial pre-cuts is provided in a singleorientation it will be apparent that the removable portions defined bythe set of planar partial pre-cuts will be slices of the body; eachslice is removable from the next slice as a result of the planarparallel partial pre-cut between them.

It is preferred that the spacing between each of the parallel planarpre-cuts in the set is 30 mm or less, preferably 25 mm or less,especially 20 mm or less, and optionally 15 mm or less. The size of theportions are defined by the spacing between the parallel planar pre-cutsin the set—in this case the slices would have a thickness correspondingto the spacing between each plane.

The partial pre-cuts sever a substantial amount of the material in theplane being cut, leaving one or more relatively narrow pieces ofmaterial attaching the portion to the body (i.e. a gap), the relativelynarrow piece of material thus forming the frangible region. It isdesirable that the partial pre-cuts define a repeating pattern ofsevered regions with intervening frangible regions, i.e. perforation. Itis preferred that the severed regions have a width of from 10 mm to 30mm, preferably from 15 mm to 25 mm, and optionally from 16 to 22 mm,especially around 18 mm, and that the remaining frangible regions have awidth of from 1 mm to 5 mm, preferably 1 to 3 mm, especially around 2mm.

In another way of considering the spacing and size of the individualpartial pre-cuts, typically the ratio of length of severed material toremaining material will be around 3 to 1 or higher (e.g. 15 mm severedand 5 mm remaining, or a ratio equivalent thereof), preferably 6 to 1 orhigher (e.g. 18 mm severed and 3 mm remaining, or a ratio equivalentthereof), especially 9 to 1 or higher (e.g. 18 mm severed and 2 mmremaining, or a ratio equivalent thereof).

In a particularly preferred embodiment the pre-cut severs from 15 to 19mm and leaves a frangible region of from 1 to 5 mm, preferably 17 to 19mm and leaves a frangible region of from 1 to 3 mm, and especiallyapproximately 18 mm leaving a frangible region of approximately 2 mmwidth.

Conveniently such a cut can be made using a die cutting apparatuscomprising an array of a set of parallel planar blades, the setcomprising a plurality of series of blades arranged in a plane, eachblade having a width corresponding to the width of the region to besevered, and a spacing between the adjacent blades within a seriescorresponding to the width of the frangible region. The spacing betweeneach planar series of blades defines the thickness of the frangibleportion.

Thus in a preferred embodiment of the invention, the wound packingmaterial comprises partial pre-cuts formed by die-cutting. Alternativemethods of forming the partial pre-cuts such as laser cutting or highpressure fluid cutting might be used as alternatives to die-cutting.

It is preferred that the body comprises a second set of parallel planarpartial pre-cuts in a second orientation. Again, it is preferred thatthe partial pre-cuts are regularly spaced, and the dimensions set outabove in relation to the first set of partial parallel planar pre-cutsare equally applicable to the second set.

The second set of partial pre-cuts may also be made by die cutting.

The second set may suitably provided at a second orientation which issubstantially perpendicular to the first orientation, i.e. where thefirst second sets of pre-cuts intersect, it will be substantially at aright angle. The pre-cuts of the first and second sets could thus besaid to lie on nominal X and Y planes respectively.

It will be apparent that where two sets of pre-cuts are provided, theselectively removable portions will typically be smaller than where oneset of partial pre-cuts is provided, i.e. the second set will sub-dividethe portions formed by the first set. Thus it could be said that thebody has a higher volumetric resolution in that it is split into finerunits.

Generally the shape of portion provided when a first and second set ofpartial pre-cuts is used will be substantially a cuboid, the width andbreadth of which is defined by the spacing of the planes in each of thepartial pre-cuts, the length being defined by the relative dimension ofthe body in a nominal Z plane. This applies for flat planar pre-cuts;where non-flat planar cuts are provided, such regular shapes will not beprovided.

It is preferred that the body comprises a third set of parallel planarpartial pre-cuts in a third orientation. Again, it is preferred that thepre-cuts are regularly spaced, and the dimensions set out above inrelation to the first and second sets of partial pre-cuts are equallyapplicable to the third set.

The third set may suitably be provided at a third orientation which issubstantially perpendicular to both the first and second set ofpre-cuts. Thus it could be said that the third set of pre-cuts lies onthe Z plane, relative to the X and Y planes of the first and second setsrespectively. Where three such sets are provided, the resultantselectively removable portions will be generally cuboids. Where thespacing between the planar partial pre-cuts are the same in each of thethree sets, the resultant selectively removable portions will besubstantially cubic.

It is of course possible to provide more than three sets of partialpre-cuts, and vary the angles between the pre-cuts to increaseresolution and provide for a greater control over the shape and size ofthe selectively removable portions. However, where more than three setsare provided, the engineering difficulties in terms of physicallyforming the pre-cuts and also in retaining the general structuralintegrity of the body become considerable. In fact, even providing threesets of cuts in the X, Y and Z planes (i.e. a 3D pre-cut body) issomewhat difficult to achieve, and it is a significant aspect of thepresent invention that this has made possible.

As mentioned above, the spacing of the parallel planar partial pre-cuts,in particular the spacing between each pre-cut plane, dictates the sizeand shape of the selectively removable portions. A spacing of 20 mm, forexample, in all 3 sets of a 3D pre-cut body provides for portions whichare cubes of approximately 20 mm in each dimension. This allows amedical practitioner to remove cube shaped portions of foam to shape thebody to the desired shape for wound packing, and to achieve a fit to theshape of the wound to within 20 mm. Alternatively, blocks of 20×20×10 mmmay be a suitable shape allowing increased resolution one dimension, butretaining a relatively manageable number of portions. It is, of course,generally desirable to allow the medical practitioner to shape the bodyof wound packing material as closely as possible to the desired shapefor wound packing, but this must be balanced against the need for easeof manufacture and simplicity of handling. It has been found that such abalance can be achieved using dimensions of from 10 to 20 mm for theremovable portions.

It should be pointed out that in certain instances it may be sufficientto have the ability to remove portions to achieve a far less preciseshape of body of wound packing material. In such situations a bodycomprising three sets of pre-cuts may not be required, and a bodycomprising one or two sets of parallel planar partial pre-cuts mayprovide sufficient scope for customisation of shape.

However, it is an objective of the present invention to provide a woundpacking material which is highly customisable, and that a bodycomprising three or more sets of parallel planar partial pre-cuts isgenerally preferred.

Accordingly, in a particularly preferred embodiment the presentinvention provides a wound packing material comprising a body of aporous material, the body comprising frangible regions defining aplurality of selectively removable cuboidal portions, the frangibleregions being defined by partial pre-cuts provided in the body of thebody.

Preferably the body is entirely comprised of selectively removablecuboidal portions interconnected by frangible regions, each of the edgesof the cuboids being 5 to 30 mm, preferably from 10 to 24 mm, especiallyfrom 10 to 20 mm.

More preferably the cuboidal portions are cubic and have an edge lengthof from 5 to 30 mm, preferably from 10 to 24 mm, especially from 10 to20 mm.

Suitably the body is generally cuboidal in shape, prior to the removalof any selectively removable portions. The body may suitably be a cube,or it may be a rectangular cuboid or square cuboid. Various shapes ofbody may be useful for different wound shapes and sizes. Typically NPWTfoam is provided as a rectangular cuboid of approximate dimensions200×100×30 mm, and this is a suitable shape for the body of the presentinvention. For such a shape and size, portions of approximately 20×20×10mm are very suitable to allow customisation of shape.

In a further aspect the present invention provides a method ofmanufacture of a wound packing material, the method comprising the stepsof:

-   -   providing a body of a porous wound packing material;    -   forming at least one partial pre-cut in a first orientation in        said body, said at least one partial pre-cut severing regions of        the body to leave frangible regions of the body, the frangible        regions allowing the portions to be selectively removed from the        body.

Preferably the at least one partial pre-cut is a parallel planar partialpre-cut.

Preferably the at least one partial pre-cut is formed by die cutting.

The die cutting may involve providing at least one blade and pushingsaid blade through the body to cut a region of the body and leave atleast one frangible region.

It is preferred that the die cutting involves providing a plurality ofblades in a suitable arrangement to provide desired partial pre-cuts andfrangible regions. Dimensions and other details of the partial pre-cutsare set out above.

Suitably the blades have a length great enough to pass completelythrough the body. It should be noted that the body may be compressed asit is cut, and therefore the blades need only be long enough to passcompletely through the body as it is compressed in the cutting process.Alternatively the blades may be shorter where it is not desirable to cutall the way through the body, or where cuts from two sides will be madeto cut completely through the body; in the latter case the blades willgenerally have a length of approximately half of the relevant dimensionof the compressed body to be cut.

The blades may suitably be arranged as an array of a set of parallelplanar flat blades, the set comprising a plurality of series ofindividual flat blades arranged in a plane, each individual flat bladehaving a width corresponding to the width of the region to be severed,and a gap between the individual flat blades corresponding to the widthof the frangible region. Suitable details of the blades are set outabove.

Suitably the method involves the step of forming a second partialpre-cut in a second orientation, especially a second set of partialpre-cuts as discussed above. Preferably the second orientation isperpendicular to the first orientation. Preferably the second partialpre-cut is a parallel planar partial pre-cut.

Suitably the method involves the step of forming a third partial pre-cutin a third orientation, especially a third set of partial pre-cuts asdiscussed above. Preferably the third orientation is perpendicular tothe first and second orientations. Preferably the third partial pre-cutis a parallel partial planar pre-cut.

Thus the method may involve providing three partial pre-cuts in nominalX, Y and Z planes. Suitably the X, Y and Z planes are congruent with thefaces of the body, where the body is a cuboid.

Suitably the method involves forming partial pre-cuts to define aplurality of regularly shaped and sized cuboidal portions interconnectedby frangible regions. Suitably the entire body is formed of selectivelyremovable cuboidal portions. Suitably the cuboidal portions are cubes.

In certain embodiments two or more sets of pre-cuts can be madesimultaneously. This can be suitably carried out using a single array ofblades comprising two sets of blades in two orientations, e.g. an arrayof cruciform blades.

Where there is a risk of excessive distortion to the body during thecutting process it is useful to support the foam structure during thecutting process.

In a further aspect of the present invention there is provided a methodof preparing a wound packing material comprising the steps of:

-   -   providing a wound packing material as set out above; and    -   removing portions of the body of said would packing material        such that the body is a desirable shape.

Preferably the body is shaped to approximately fit the shape of a woundto be packed.

Preferably the portions are removed manually, i.e. without the use oftools.

In a further aspect the present invention provides a method of treatinga wound comprising the steps of;

-   -   providing a wound packing material as set out above;    -   removing portions of the body of said would packing material        such that the body is a desirable shape to fit within said        wound; and    -   packing the wound with said wound packing material.

Preferably the method provides the step of applying a negative pressureto the wound through the wound packing material, i.e. the method isNPWT. In general this can be achieved by providing a substantially fluidimpermeable sheet over the wound and wound dressing, thus defining asealed volume, and applying a negative pressure inside said sealedvolume. The seal need not be completely hermetic, but should besufficient to allow a suitable negative pressure to be sustained. Thesource of negative pressure, e.g. a pipe form a vacuum pump, is providedat a position such that it draws fluids from the wound bed through thewound packing material.

Suitably the negative pressure is in the range of from 80 to 125 mm Hgbelow ambient atmospheric pressure.

In a further aspect the present invention provides the use of a woundpacking material as set out above in wound treatment, especially NPWT.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the present invention will now be described, by way ofexample only, with reference to the accompanying drawings, in which:

FIG. 1 shows a body of porous wound packing material after being pre-cutin the x, y and z dimensions;

FIG. 2 schematically shows the set of pre-cuts in the x and y dimension;

FIG. 3 schematically shows the sets of pre-cuts in the z dimension;

FIG. 4 shows a body with a single portion removed;

FIG. 5 shows the body of FIG. 4 with a plurality of portions removed;

FIG. 6 shows a first array of a set of blades suitable for forming apartial pre-cut in a first orientation in a body of wound packingmaterial; and

FIG. 7 shows a second array of sets of blades suitable for making secondand third sets of partial pre-cuts in a body of wound packing materialin second and third orientations;

DETAILED DESCRIPTION OF SOME EXEMPLIFYING EMBODIMENTS

As shown in FIG. 1, a body 10 of porous material, such as foam, isgenerally a cube in shape having three dimensions, x, y and z. Theporous material is suitable for wound packing. The material may bereticulated polyurethane foam of very high free internal volume. Thebody 10 could be a different shape, e.g. a comparatively flat cuboid,which is a conventional shape for foams for NPWT.

As shown in FIG. 2, the body 10 is partially pre-cut by a suitablecutting technique, such as die cutting (though other techniques may beuseable), in the planes in the x and y dimensions to define a first andsecond set of parallel planar partial pre-cuts 14, 16. The body 10 isalso partially pre-cut in the z dimension to define a third set ofparallel planar partial pre-cut 18. The three sets of partial pre-cuts14, 16, 18 define individual cubic portions 12 of approximately equalvolume.

The three sets of partial pre-cuts 14, 16, 18 are intermittent, the gapsin the pre-cuts defining frangible regions 20 on each internal face ofeach portion 12 (in other words they are perforated for easy removal ofthe portions). The frangible regions 20 connect adjacent portions 12together thereby to ensure the portions 12 remain connected togetherwhen the body 10 is stored, compressed or extended, i.e. when being usedas a wound packing in NPWT.

The frangible regions 20 extend between face sides of each portion 12and are elongate. The thickness of each frangible region 20 is suitableto provide adequate strength to ensure adjacent portions 12 remainconnected when the body 10 is being compressed or extended during normaluse, whilst allowing one or more portions 12 to be easily pulled fromthe body 10 by compromising the integrity of the frangible regions 20attaching the portion 12 to the body. For typical NPWT foams, afrangible region of approximately 2 mm of thickness provides a goodcompromise of strength versus tearability.

One or more portions 12 can be selectively removed by hand from the body10 to shape the body 10 for a particular wound packing application.Advantageously, cutting tools such as knives, scalpels and scissors arenot required to shape the body 10 of porous material.

As shown in FIGS. 4 and 5, the body 10 is a cube of volume 448000 mm³,which is pre-cut in the x, y and z dimensions to define 448 (i.e. 7×8×8)equally sized 1000 mm³ portions 12 (i.e. 10×10×10 mm). Adjacent portions12 are connected by a frangible portion 20 of 2 mm thick porous material(not shown).

The frangible regions 20 ensure the body 10 retains its structuralintegrity for storage and handling purposes whilst allowing one or moreportions 12 to be selectively removed therefrom. FIG. 4 shows a singleportion 12 removed from the body 10 to leave a hole 22, whilst FIG. 5shows a plurality of portions 12 removed from the body 10 to selectivelyshape the body 10 for a particular application of wound packing. Thebody 10 may be shaped to complement the external contours of a patientor to fit in a cavity.

Of course, the dimensions of the body 10 and the portions 12 may bedifferent to those described above for a particular application and thenumber and orientation of partial pre-cuts lines 14, 16, 18 may bevaried and may be planar or curved to define regular or irregularportions 12 accordingly.

To form a wound packing material similar to the above the followinggeneral process may be used. The present process describes a process forconverting a single cuboid block of foam into 6 cuboidal wound packingmaterial bodies. The block is initially approximately 200 mm by 100 mmby 180 mm and is cut into 6 blocks of 200 mm by 100 mm by 30 mm. It willbe apparent that variations of this method could be used to manufacturewound packing materials of a great variety of different shapes andsizes, and having varying portion size and shapes.

-   -   A body of porous material is provided which has the dimensions        set out above.    -   A first set of parallel planar partial pre-cuts is made in the        body using an array of blades 30. The pre-cuts are made        perpendicular to, and into, a first face of the body    -   The array (FIG. 6) comprises a number of planes 31 made up of a        series of 18 mm wide flat blades 32, and a 9 mm blade 33 at each        end of the plane; a gap of 2 mm is provided between each blade        in the series. A gap of 10 mm is left between each plane of        blades. The array also comprises 5 continuous 100 mm long planar        blades 36 which acts to cut the initial block completely into 6        smaller blocks.    -   The first set of partial pre-cuts is achieved by placing the        block of foam against the array of blades 30 and urging the        blades into and through the block. The pressure required may be        generated by a hydraulic press (also known as a clicker press).        This is a conventional form of die cutting and the necessary        apparatus and techniques are well known to one skilled in the        art.    -   Second and third sets of partial pre-cuts are made using a        second array 40 of blades (see FIG. 7). In the second array a        plurality of cruciform blades 42 are provided. Due to the shape        and arrangement of the blades 42, the array is suitable to make        two sets of parallel planar partial pre-cuts in two        orientations, which are perpendicular to each other. Thus, in        one cutting action, two sets of parallel planar partial pre-cuts        are made. Each cruciform blade 42 comprises two 18 mm long        linear blade elements 44,46 intercepting at each of their        midpoints at a right angle to define the cruciform blade.    -   The cruciform blades are arranged in the array to form a square        matrix with gaps of 2 mm provided between each cruciform blade.    -   As with the first cut, the second cut is made by applying        pressure to drive the blades 42 through the body.    -   The length of the blades in the first and second array are        sufficient to pass completely through the body and emerge at the        other side.

This process forms 6 cuboids of foam measuring 200 mm×100 mm×30 mm,which are each formed of cuboids measuring approximately 20 mm×20 mm×10mm, each of the cuboid portions being interconnected with adjacentportions by frangible regions of approximately 2 mm thickness.

It should be noted that where a generally cubic body of foam is beingprepared the order of the cuts is not particularly significant as thecube is equally structurally stable in all 3 dimensions. However, whenpreparing a body with a relatively thin minor dimension, as set out inthe method above, it is important that the first cut made is the oneperpendicular to the plane of the thin dimension (i.e. the smallest faceof the cuboid), or that the shape of the block is supported as the cutis made. If the order is reversed, or the block shape is not supported,there is generally an unacceptable amount of crushing and/or corrugationof the body resulting in a significant distortion to the desired cutgeometry.

The result of this process is a wound packing material which can becustom shaped by manually removing cuboid portions by tearing thefrangible regions interconnecting the portions making up the body. Thisallows a medical practitioner to shape the body of wound packingmaterial to fit the wound to be packed or dressed. Once the woundpacking material has been shaped appropriately, the wound can be dressedfor NPWT.

1-37. (canceled)
 38. A negative pressure wound treatment apparatus,comprising: a body of porous material, the body comprising a pluralityof outer surfaces and a plurality of outer edges, each of the pluralityof outer edges disposed at an interface of a pair of adjacent outersurfaces, the body comprising an array of partial pre-cuts, the array ofpartial pre-cuts comprising a plurality of first cuts extending in afirst direction and a plurality of second cuts extending in a seconddirection, individual first cuts intersecting with individual secondcuts; and a cover layer positioned over the body of porous material, thecover layer comprising an opening configured to communicate negativepressure, the opening configured to connect to a source of negativepressure.
 39. The negative pressure treatment apparatus of claim 38,wherein individual first cuts are perpendicular to individual secondcuts.
 40. The negative pressure treatment apparatus of claim 38, whereinthe porous material comprises foam.
 41. The negative pressure treatmentapparatus of claim 40, wherein the foam comprises polyurethane.
 42. Thenegative pressure treatment apparatus of claim 38, wherein individualfirst cuts extend from a first outer edge to a second outer edge. 43.The negative pressure treatment apparatus of claim 42, whereinindividual first cuts extend across the entire length of the body ofporous material.
 44. The negative pressure treatment apparatus of claim38, wherein individual second cuts extend from a third outer edge to afourth outer edge.
 45. The negative pressure treatment apparatus ofclaim 44, wherein individual second cuts extend across the entire widthof the body of porous material.
 46. The negative pressure treatmentapparatus of claim 44, further comprising a connector configured toconnect to a source of negative pressure.
 47. The negative pressuretreatment apparatus of claim 46, further comprising a source of negativepressure.
 48. The negative pressure treatment apparatus of claim 38,wherein the porous material is formed from a wound packing materialsuitable for use in negative pressure wound therapy.
 49. The negativepressure treatment apparatus of claim 38, wherein the porous material isconfigured such that it does not substantially collapse when negativepressure is applied.
 50. The negative pressure treatment apparatus ofclaim 49, wherein the negative pressure is in the range of 80 to 125 mmHg below ambient atmospheric pressure.
 51. The negative pressuretreatment apparatus of claim 38, wherein the partial pre-cuts are formedduring initial production of the body of porous material.
 52. Thenegative pressure treatment apparatus of claim 38, wherein individualpartial precuts are generally planar.
 53. The negative pressuretreatment apparatus of claim 38, wherein the plurality of first cuts areregularly shaped.
 54. The negative pressure treatment apparatus of claim53, wherein the plurality of second cuts are regularly spaced.
 55. Thenegative pressure treatment apparatus of claim 38, wherein the pluralityof first cuts are parallel.
 56. The negative pressure treatmentapparatus of claim 55, wherein the plurality of second cuts areparallel.